import javax.swing.tree.TreeNode;

/**
 * \* Created with IntelliJ IDEA.
 * \* User: 冯若航
 * \* Date: 2021/5/12
 * \* Time: 1:34
 * \* To change this template use File | Settings | File Templates.
 * \* Description:
 * \
 */
public class 对称二叉树 {
    public class TreeNode {
        int val;
        TreeNode left;
        TreeNode right;
        TreeNode() {}
        TreeNode(int val) { this.val = val; }
        TreeNode(int val, TreeNode left, TreeNode right) {
            this.val = val;
            this.left = left;
            this.right = right;
        }
    }
    public boolean isSymmetric(TreeNode root) {
        return check(root,root);
    }
    public boolean check(TreeNode p,TreeNode q){
        if (p == null && q == null) {
            return true;
        }
        if (p == null || q == null) {
            return false;
        }
        if(p.val!=q.val){
            return false;
        }
        return check(p.left,q.right)&&check(p.right,q.left);
    }
}